The present invention relates to the management of industrial waste streams. More particularly the invention is concerned with improvements in the desulfurization of effluent gases using high alkalinity water produced in industrial processes such as in bitumen recovery and tar sands mining and extraction.
Sulfur containing effluent gas streams are a byproduct of many industrial processes. For example, produced gases associated with the steam-based recovery of bitumen from oil sands contain primarily methane, CO2, minor amounts of C6 or lower alkanes and H2S in amounts of about 0.5 mole % or so. Combustion of these H2S containing gas streams, of course, results in the formation of SO2 which becomes a component of the flue gas. In order to meet environmental requirements it is necessary to remove the SO2 from such effluent flue gas streams.
Typically the SO2 present in effluent flue gas streams resulting from the combustion of fuels that contain H2S or other sulfur compounds is removed from the effluent stream by one of a variety of scrubbing techniques. For example, one technique involves scrubbing the gas with an aqueous solution of sodium hydroxide or ammonia. This, of course, suffers from the disadvantage of having to purchase, store and mix the requisite reagent, as well as dispose of the resulting waste material.
Another technique for removing SO2 from flue gas involves scrubbing the effluent with seawater. Seawater scrubbing, of course, is limited to use at facilities in the immediate vicinity of a seawater source. Additionally, the used seawater must be diluted and its pH buffered with fresh seawater before it can be disposed of and this incurs additional pumping expense.
Yet another scrubbing technique utilizes a limestone slurry or variations thereof. Although limestone slurry processes and modifications thereof are the most widely used method of flue gas desulfurization, they result in the formation of a spent slurry that needs to be disposed of by land farming or other means.
In U.S. Pat. No. 3,844,349 there is disclosed a process for producing petroleum by steam injection into a petroleum-bearing formation in which the steam is generated by firing a steam generator with a sulfur containing fuel. The resultant flue gas is scrubbed with alkaline water obtained from the petroleum bearing formation. This technique requires pumping large volumes of flue gas for treatment and exposes the steam generators to potentially corrosive conditions.
In view of the foregoing, there remains a need for improvements in processing waste streams such as those generated in burning the gas obtained as a byproduct in bitumen production which is highly effective, practical and economically attractive.
Broadly stated, the present invention provides a process for the management of industrial waste streams comprising H2S containing gas streams and high alkalinity water streams in which process the H2S is selectively removed from the gas stream and combusted to form an SO2 rich waste gas stream which is scrubbed with the high alkalinity water thereby substantially removing the SO2 from the gas stream.